UC Riverside

Irrigated agriculture has been in a quandary of sustaining its productivity for centuries while attempting to cope with soil and water salinity issues that continue to devastate crop yields. Several of the research gaps associated with current irrigation methods include how to assess leaching requirements and efficiency for different soils, crops, and irrigation regimes. The objective of this project was to test water application methods on salinity leaching efficacy. Three soils of different textures (clay, loam, and sandy soils) were collected from fields. The soils were air-dried and sieved (1.7 mm) and were used to pack the soil columns (10-cm dia. and 30-cm height) for the leaching experiments. Treatments of the column experiments included continuous ponding, intermittent ponding, and unsaturated water application with three replicates per treatment using the three soils. Furthermore, the HYDRUS 1D model was used to analyze the experimental data and to evaluate the leaching efficiency under different irrigation schemes. Our results showed that intermittent ponding was the most effective water application method for salinity leaching in the loamy soil, and that the unsaturated water application was the most effective water application method for salinity leaching in the clay soil by achieving 75% salt removal out of the columns using the least amount of water. The sandy soil had no difference in leaching efficiency among water application methods, therefore continuous ponding is recommended if time is not a limiting factor in water supply. The findings from this research will allow farmers to improve their water management practices and reduce groundwater contamination from excessive irrigation.